Best definition
Weather Girl
A girl that brightins up ur day when ur sad.

“Whenever im sad my weather girl cheers me up.”
Weather Girl: define #2
The yummiest of all the Z-list celebrities. To be a weathergirl you must be either blonde or brunette or redhed, and you must be very pretty and have a great body. If you wish to be a weathergirl, being swedish is of benefit but not a requirement. Famous weathergirls include Ulrika Johnson and bald-headed-moustache-man Michael Fish. If you see a weathergirl, steer clear of them as they will have an IQ of roughly 3, and this may cause them to spontaneously combust.
Kevin: “Who’s that nobody?”

Phil: “Just some weathergirl.”

Kevin: “Hmm, hottie.”